Table 1. Patient demographics and risk factors in RA.

Variable	Cases (n=574)	Controls (n=804)	P
Age (years)	54.5 ± 15.1	55.7 ± 10.1	0.080
Female/male	427/147	599/205	0.962
Onset age (years)	45.6 ± 12.9
Disease duration (years)	8.9 ± 9.2
Treatment duration (years)	7.6 ± 7.8
RF-positive	456 (79.4%)
ACPA positive	300 (52.2%)
CRP-positive	323 (56.3%)
ESR (mm/h)	33.7 ± 25.2
DAS28	4.3 ± 1.5
Functional class
I	73 (12.7%)
II	256 (44.6%)
III	209 (36.4%)
IV	36 (6.3%)

Abbreviations: CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; DAS28, RA disease activity score; RF, rheumatoid factor.